Field Testing And Numerical Analysis On The Composite Soil-Nailing At Gome Shoppingcity Foundation Pit

The prestressed anchor composite soil-nailing, a common and effective method of composite soil-nailing supporting, combines soil-nailing with prestressed anchor. Through this method, the deformation of foundation ditch can be effectively controlled, and the stability of slope can be improved.Currently, it is not enough far away in understanding to the stress and deformation of this method for a few researches on the method and shortage of field test data, in addition, it is considered as a plane problem in the finite element analysis. On the basis of field testing and numerical analysis from the case of Gome Shoppingcity foundation pit, research is expected to reveal the characteristics of internal force and deformation of the method, so as to provide scientific basis for its design and construction.The development, research and prospects of application of composite soil-nailing are summarized, the deficiency of present research on the technique is presented, and the mechanism of composite soil-nailing is explained, moreover, lateral earth stress distribution is analysed. Based on field testing and numerical analysis, the internal force and deformation of the prestressed anchor composite soil-nailing at Gome Shoppingcity deep foundation pit is studied. The results show that:①The horizontal deformation of foundation ditch can be suppressed effectively adopting this type of composite soil-nailing, the maximum horizontal deformation occurs at the mid-bottom part of pit;②The soil nailing has an excavation effect, that is, all the soil nails that have been set up are affected by the lower soil excavation.③Distributions of stress along the length of soil nails show that the tensile stresses in the middle part are large, small in the end;④The process of foundation excavation has little influence on the pressures on the top of the anchor after the anchor is prestressed;⑤Practice proves that in the sand and gravel layer in which soil is more homogeneous, more stable, and site condition is permitted, it is feasible to adopt soil-nailing supporting in the deep foundation ditch, so project cost can be greatly reduced and time is shortened.